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Povzetek: Electrochemical signals are traditionally interpreted in the time domain, where overlapping faradaic and non-faradaic currents, noise, and drift obscure frequency-dependent behaviour. This study introduces a frequency-domain framework that complements time-domain analysis by decomposing voltammetric signals into their harmonic components through Fourier methods. AC voltammetry provides experimental evidence of how increasing excitation frequency progressively suppresses faradaic clarity, while a modified Randles equivalent circuit model explains this response through the interplay of charge-transfer, diffusion, and double-layer charging processes. Fourier series analysis of canonical voltammetric techniques, including linear sweep, cyclic, differential pulse, and square wave voltammetry, shows that waveform geometry uniquely defines harmonic structure. Fast Fourier transform analysis of practical data reveals artefacts introduced by finite sampling, binning, and spectral leakage. These effects highlight the need for conceptual awareness when interpreting experimental spectra. Quantitative spectral descriptors such as the centroid, bandwidth, flatness, and low-frequency power fraction link waveform design directly to faradaic visibility and measurement clarity. Frequency-domain analysis therefore establishes that electrochemical measurement is inherently frequency-structured. By combining experimental data, equivalent circuit modelling and spectral metrics within a single framework, this approach provides a general route to optimise waveform parameters, reduce capacitive interference, and improve interpretability across electrochemical techniques. Viewed more broadly, this perspective reframes the process of the measurement itself, showing that time-domain signals are projections of an underlying spectral reality.
Ključne besede: frequency domain, spectral decomposition, electrochemical sensors, benzenediols
Objavljeno v DiRROS: 22.12.2025; Ogledov: 936; Prenosov: 298
Celotno besedilo (6,14 MB)
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Povzetek: Simple, low-cost methods for sensing volatile organic compounds that leave no trace and do not have a detrimental effect on the environment are able to protect communities from the impacts of contaminants in water supplies. This paper reports the development of a portable, autonomous, Internet of Things (IoT) electrochemical sensor for detecting formaldehyde in tap water. The sensor is assembled from electronics, i.e., a custom-designed sensor platform and developed HCHO detection system based on Ni(OH)2–Ni nanowires (NWs) and synthetic-paper-based, screen-printed electrodes (pSPEs). The sensor platform, consisting of the IoT technology, a Wi-Fi communication system, and a miniaturized potentiostat can be easily connected to the Ni(OH)2–Ni NWs and pSPEs via a three-terminal electrode. The custom-made sensor, which has a detection capability of 0.8 µM/24 ppb, was tested for an amperometric determination of the HCHO in deionized (DI) and tap-water-based alkaline electrolytes. This promising concept of an electrochemical IoT sensor that is easy to operate, rapid, and affordable (it is considerably cheaper than any lab-grade potentiostat) could lead to the straightforward detection of HCHO in tap water.
Ključne besede: formaldehyde, electrochemical sensor, nickel, tap water
Objavljeno v DiRROS: 06.06.2023; Ogledov: 1934; Prenosov: 1536
Celotno besedilo (2,65 MB)
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